U.S. Provisional Application No. 60/431,814 filed Dec. 9, 2002 discloses a method for preparing the intermediate (5S)-5-aminocarbonyl-4,5-dihydro-1H-pyrrole-1-carboxylic acid, 1-(1,1-dimethylethyl)ester (Formula A)
from 4,5-dihydro-1H-pyrrole-1,5-dicarboxylic acid, 1-(1,1-dimethylethyl)-5-ethyl or methyl ester (Formula B)
by hydrolyzing B by saponification with lithium hydroxide, and treating with mesyl chloride and ammonia to produce the Formula A intermediate.
The Formula A intermediate is useful in preparing the dipeptidyl peptidase IV inhibitor (1S,3S,5S)-2-[(2S)-2-amino-2-(3-hydroxytricyclo[3.3.1.13,7]dec-1-yl)-1-oxoethyl]-2-azabicyclo[3.1.0]hexane-3-carbonitrile
(disclosed in U.S. Pat. No. 6,395,767 which is incorporated herein by reference) as discussed in U.S. Provisional Application No. 60/431,814 which is useful in treating diabetes.